A tunnel boring machine (“TBM”) is a tunnel excavation apparatus that is typically used to form circular tunnels in a variety of soil and rock strata. A conventional TBM produces a smooth circular tunnel wall, typically with minimal collateral disturbance. A breakthrough that made TBMs efficient and reliable was the invention of the rotating head, developed by James S. Robbins. Initially, Robbins' TBM used strong spikes rotating in a circular motion, but the spikes would break frequently. He discovered that by replacing these grinding spikes with longer lasting rotating cutter assemblies this problem was significantly reduced. Since then, all successful modern TBMs have rotating cutter assemblies.
Since the advent of tunnel boring machines, operators and manufacturers of these machines have desired to understand and monitor how the cutting devices interact with the material being bored. Real time performance data would allow the operator to improve the efficiency and reliability of the tunnel boring operation by controlling certain operating parameters and performing timely maintenance. For example, costly delays due to component failures can be avoided by monitoring the tunnel boring machine in real-time, in order to quickly identify problems, allowing the operator to initiate appropriate corrective actions.
Additionally, machine manufacturers can adjust the design of components based on this data. Previous attempts to develop rational operating and maintenance schedules for tunnel boring machines have included the use of theoretical mathematical models, with or without simple force measurement devices, and inference of the interactions through ancillary evidence provided by operating conditions of the machine itself. Illustrative tunnel boring machines are disclosed in U.S. Pat. No. 4,548,443 and U.S. Pat. No. RE 31511, both of which are hereby incorporated by reference in their entirety. Additional illustrative prior art tunnel boring machines are disclosed in U.S. Pat. No. 5,205,613 and U.S. Pat. No. 6,431,653, both of which are hereby incorporated by reference in their entirety. U.S. Pat. No. 5,308,151 to Sugden, et al. discloses a different type of mining machine with cutters that are provided with cutter shaft strain gauges to provide a measure of the direct load on one or more roller cutter assemblies. One or more of the cutter shafts are provided with a strain gauge to provide a measure of the direct load on the roller cutter assembly. However, simple strain gauge measurements do not provide desired information on the operating performance and rotating characteristics of the cutter assemblies.
There remains a need for systems capable of providing real-time monitoring of the performance of individual cutters on tunnel boring machines, which could be used to provide early detection of problems with individual cutters, to provide information that may be used to control the machine to optimize performance and avoid unnecessary wear, and/or to monitor the conditions of the rock or other material being bored.